diff --git a/.jules/sentinel.md b/.jules/sentinel.md
index bc5c6e1..1a76cd5 100644
--- a/.jules/sentinel.md
+++ b/.jules/sentinel.md
@@ -12,3 +12,7 @@
 **Vulnerability:** Raw `stop()` and `warning()` calls without `call. = FALSE` in `llcont.R` and `vuongtest.R` exposed execution stack/call details when raised.
 **Learning:** While some instances of `stop()` inside `tryCatch()` were previously fixed to hide the call stack, other standalone exceptions and warnings still leaked call context. Security must be consistently applied across the entire codebase.
 **Prevention:** Always set `call. = FALSE` when using `stop()` or `warning()` to enforce a secure-by-default boundary and prevent internal execution paths from being disclosed to the end user.
+## 2024-08-15 - Missing Argument Validation Exposing Internal Context
+**Vulnerability:** The top-level functions `vuongtest()` and `icci()` accepted user inputs (e.g. vectors for boolean or choice parameters) without validation, which bypassed initial code guards and resulted in deep internal R errors like "the condition has length > 1". This exposes internal execution stack frames and implementation details to the user.
+**Learning:** In R codebases, it is critical to actively validate the types and lengths of arguments passed to exported functions immediately upon entry to prevent unexpected error behaviors down the call stack.
+**Prevention:** Always strictly validate argument types, lengths, and valid choice sets right at the start of any exported function. Ensure failure conditions use `stop(msg, call. = FALSE)` to fail securely.
diff --git a/R/icci.R b/R/icci.R
index f22278a..140485c 100644
--- a/R/icci.R
+++ b/R/icci.R
@@ -65,6 +65,8 @@
 #' @export
 icci <- function(object1, object2, conf.level=.95, ll1=llcont, ll2=llcont) {
 
+  if(!is.numeric(conf.level) || length(conf.level) != 1 || is.na(conf.level) || conf.level <= 0 || conf.level >= 1) stop("conf.level must be a single numeric value between 0 and 1", call. = FALSE)
+
   ## check objects, issue warnings/errors, get classes/calls
   obinfo <- check.obj(object1, object2)
   callA <- obinfo$callA; classA <- obinfo$classA
diff --git a/R/vuongtest.R b/R/vuongtest.R
index 2bdfbf6..6010f6f 100644
--- a/R/vuongtest.R
+++ b/R/vuongtest.R
@@ -98,6 +98,9 @@
 #' @export
 vuongtest <- function(object1, object2, nested=FALSE, adj="none", ll1=llcont, ll2=llcont, score1=NULL, score2=NULL, vc1=vcov, vc2=vcov) {
 
+  if(!is.logical(nested) || length(nested) != 1 || is.na(nested)) stop("nested must be a single logical value", call. = FALSE)
+  if(!is.character(adj) || length(adj) != 1 || !(adj %in% c("none", "aic", "bic"))) stop("adj must be one of 'none', 'aic', or 'bic'", call. = FALSE)
+
   ## check objects, issue warnings/errors, get classes/calls
   obinfo <- check.obj(object1, object2)
   callA <- obinfo$callA; classA <- obinfo$classA